This invention relates generally to transport refrigeration systems, and more particularly, to heat shields arranged between the tractor and the trailer of a transport refrigeration system.
Refrigerated trucks, trailers, and intermodal containers, collectively mobile refrigeration systems, are commonly used to transport perishable cargo, such as, for example, meat, poultry, dairy products, cut flowers, and other fresh or frozen products, by road, rail, sea, or intermodally. In the case or refrigerated trucks, a transport refrigeration system is mounted to the truck, typically behind the truck or on the roof of the truck for maintaining a controller temperature environment within the cargo box within the truck. In the case of refrigerated trailers, which are typically pulled behind a tractor vehicle, a transport refrigeration system is mounted to the trailer, typically to the front wall of the trailer for maintaining a controlled temperature environment within the cargo box of the trailer.
Conventionally, transport refrigeration systems used in connection with refrigerated trucks and refrigerated trailers include a transport refrigeration unit having a refrigerant compressor, a condenser with one or more associated condenser fans, an expansion device, and an evaporator, with one or more associated evaporator fans, which are connected via appropriate refrigerant lines in a closed refrigerant flow circuit. Air or an air/gas mixture is drawn from the interior volume of the cargo box by means of the evaporator fan(s) associated with the evaporator, passed through the airside of the evaporator in heat exchange relationship with refrigerant whereby the refrigerant absorbs heat from the air, thereby cooling the air. The cooled air is then supplied back to the cargo box.
During operation of the transport refrigeration system, particularly for tractor-trailer systems, hot air from cooling the prime mover of the engine of the tractor is expelled between the tractor and the trailer near the condenser air inlet of the transport refrigeration unit. In addition, hot air is similarly discharged from the bottom of the transportation refrigeration unit. The condenser of the transport refrigeration unit draws in a mixture of the ambient air and the discharged air from both the tractor engine and the trailer refrigeration unit and uses that air mixture to absorb heat from the refrigerant flowing through the condenser. The increased temperature of the discharged air reduces the efficiency of the condenser and therefore the transport refrigeration unit.